Some magnetofluid cosmological models of plane symmetry

Considering the cylindrically-symmetric metric of Marder, some plane-symmetric magnetofluid cosmological models have been derived. Various physical and geometrical properties of the models have been discussed.     

Some anisotropic spatially-homogeneous cosmological models with electromagnetic field

Considering Bianchi type-I metric, cosmological models of a perfect fluid with an electromagnetic field have been obtained, using a supplementary condition between the metric potentials. The four-current is either zero or space-like. The model has expanding and shearing but non-rotating fluid flow which is also geodetic. The requirement of positive conductivity imposes an additional restriction on the model. Various physical and mathematical properties of the model have been discussed.     

Expanding and shearing inhomogeneous cosmological models for viscous fluid distributions with electromagnetic field

Some inhomogeneous viscous fluid cosmological models in the presence of an electromagnetic field for cylindrical symmetry are obtained. To get a determinate solution, it is assumed that the coefficient of shear viscosity is proportional to the rate of expansion. The paper also discusses the behaviour of the model when viscosity is absent and comments on some other physical properties.     

Some plane symmetric inhomogeneous cosmological models in the scalar-tensor theory of gravitation

The present study deals with the inhomogeneous plane symmetric models in scalar-tensor theory of gravitation. We used symmetry group analysis method to solve the field equations analytically. A new class of similarity solutions have been obtained by considering the inhomogeneous nature of metric potential. The physical behavior and geometrical aspects of the derived models are also discussed.     

Cylindrically symmetric and inhomogeneous cosmological models with viscous fluid,heat flux and electromagnetic field

In this paper cylindrically symmetric, inhomogeneous cosmological models with heat flux, viscous fluid and electromagnetic field are obtained. Various physical and geometrical properties of the models are also discussed.     

Bulk viscous string cosmological models with electromagnetic field

LRS Bianchi type-I string cosmological models are studied in the frame work of general relativity when the source for the energy momentum tensor is a bulk viscous stiff fluid containing one dimensional strings embedded in electromagnetic field. The bulk viscosity is assumed to be inversely proportional to the scalar expansion. The physical and kinematical properties of the models are discussed. The effects of Viscosity and electromagnetic field on the physical and kinematical properties are also investigated.     

Inhomogeneous cosmological models with electromagnetic field in general relativity

In this paper inhomogeneous cosmological models with perfect fluid distributions in presence of electromagnetic field is obtained. Various physical and geometrical properties of the model in presence of electromagnetic field are also discussed.     

A plane-symmetric inhomogeneous cosmological model of perfect fluid distribution with electromagnetic field

A plane-symmetric inhomogeneous cosmological model of perfect fluid distribution with electromagnetic field, is obtained.F ₁₂ is the non-vanishing component of the electromagnetic field tensor. To get a determinate solution, we assume the free gravitational field is Petrov type-II non-degenerate. In general, the model represents an expanding, shearing, non-rotating universe in which the flow vector is geodetic. The behaviour of the electromagnetic field tensor together with some geometrical and physical aspect of the model are also discussed.     

Evolution of inhomogeneous cosmological models with viscous fluids

We show the evolution of the Szekeres's cosmological models of class II with dissipative fluids and we study under which conditions these tend to the homogeneous and isotropic models.     

Exact Bianchi type VIo cosmological models with matter and an electromagnetic field

Self-similar solution for isothermal flows driven by an expanding piston are investigated in the presence of magnetic field. The total energy of the flow between the shock and the piston is taken to be dependent on time obeying a power law. The shock is assumed to be strong and propagating into a perfect gas at rest with non uniform density and magnetic field.     

Shear-free and cavity models with plane symmetry

This paper aims to explore anisotropic planar analytical models for dissipative as well as non-dissipative matter distributions. We relate the Weyl tensor and physical variables of matter distribution. Darmois junction conditions are formulated on internal and external hypersurfaces. It is found that our dissipative models show the presence of cavity with non-zero expansion. Finally, we investigate two types of solutions with zero shear as well as heat flux by a specific choice of the mass function and by restricting pressure.     

Some cosmological models with spin and torsion

In axially-symmetric cosmological models of the Einstein-Cartan theory (which may be briefly called general relativity plus spin), the axis of symmetry is at the same time the direction of the magnetic field, and of the aligned spins. The general set of relevant equations is given. Some exact solutions of this set constitute quasi-Euclidean and semiclosed cosmologies with a uniform magnetic field and aligned spinning matter. In contrast to the situation in the framework of general relativity, one may obtain non-singular solutions. Such a behaviour of the solutions of the Einstein-Cartan theory is rendered possible by the specific spin-spin repulsive interaction which is inherent in the theory.     

Higher dimensional inhomogeneous cosmological models in Lyra geometry

We have presented in homogeneous cosmological models within the framework of Lyra geometry. We have considered an inhomogeneous spherically symmetric higher dimensional model in presence of a mass less scalar field whose potential has a flat part. The scalar field is considered to be inhomogeneous. Also an inhomogeneous cosmological model is derived in a Kaluza-Klein type of space time. The matter field is taken as an inhomogeneous distribution of fluid. It is observed that there is no singularity at finite past in our model and the desirable feature of dimensional reduction is also possible for the extra space. This revised version was published online in July 2006 with corrections to the Cover Date.     

Magneto-viscous fluid cosmological model of plane symmetry in general relativity

The object of this paper is to investigate the behaviour of magnetic field in a viscous fluid cosmological model. Various physical and geometrical properties of the model have also been discussed.     

Some cosmological models with spin and torsion,I

The Einstein-Cartan theory, which is a slight modification of the general theory of relativity, is almost indistinguishable in its practical consequences from the latter theory. A characteristic spin-spin repulsive interaction which is of some importance at ultraheavy densities, prevents the singularities occurring in the Einstein-Cartan treatment. It is shown how this mechanism of preventing the singularity applies to cosmological models in which the spins of matter are aligned along some symmetry axis. Some exact solutions without singularities of the relevant set of equations are obtained.     

Inhomogeneous viscous fluid cosmological model with electromagnetic field in general relativity

The object of this paper is to investigate the behaviour of electromagnetic field in inhomogeneous cosmological models obtained for viscous fluid distributions. The various particular cases when both the electromagnetic and viscosity are absent, are also discussed.     

Bianchi type-VI0 perfect fluid cosmological models with magnetic field

In this paper we discuss Bianchi type-VI₀ cosmological models with perfect fluid distribution and magnetic field directed along the axial direction. Einstein's equations have been solved for the condition that the expansion scalar bears a constant ratio to the anisotropy in the direction of a space-like unit vector ⁱ.     

Cylindrically symmetric inhomogeneous universe with electromagnetic field in string cosmology

Cylindrically symmetric inhomogeneous string cosmological model in presence of electromagnetic field is investigated. We have assumed that F ₂₃ is the only non-vanishing component of F _ij . To get the deterministic solution, it has been assumed that the expansion (θ) in the model is proportional to the eigen value σ ¹ ₁ of the shear tensor σ ⁱ _j . The physical and geometric aspects of the model are also discussed.      

An inhomogeneous stiff fluid universe with electromagnetic field in general relativity

An inhomogeneous cylindrically symmetric cosmological model for stiff perfect fluid distribution with electromagnetic field is obtained.F ₁₂ is the non-vanishing component of electromagnetic field tensor. The metric potentials are functions ofx andt both. The behaviour of the electromagnetic field tensor together with geometrical and physical aspects of the model are also examined.